Device for measuring the degree of adhesion of vehicle wheels to their tracks



Fb. 7, T95@ Filed March 25, 1946 JEAN THOORE FOUFOUNIS, ALRAS JEAN MICHEL PAILLAIS DEVICE FOR MEASURING THE DEGREE OF ADHESION OF VEHICLE WHEELS T0 THEIR TRACKS 2 Sheets-Sheet l /NVEN Toe ATTORNE YS JEA Z750/9025 Foafowvw Feb. 195@ JEAN THEoDoRE FounffoLms, 2949405 ALIAS JEAN MICHEL PAILLAHS DEVICE FOR MEASURING THE DEGREE 0F' ADHESION OF' VEHICLE WHEELS T0 THEIR TRACKS 2 Sheets-Sheet 2 Filed March '25, 1946 fwd Mw m E w T M Y B HLIAS, JEANMCHEL JDAILL als Patented Feb. 7, 1950 UNITED .STATES PATENT OFFICE .DEVICE 'FOR `MEASURNG THE DEGREE OF ADHESION F VEHICLE WHEELS TO THEIR/*TRACKS Jean Thodore Foufounis, alias Jean Michel Paillais, Paris, France Application March L25, 1946, Serial No. 657,000 .In France January 5, 1945 seccion .1., Public Law 69o, August s, 1946 "Patent expires January 5, 1965 9 Claims. 1

The device essentially comprises Ian Yadhesion feeling member yieldingly urged :toward the surface over which the `vehicle -trave'lsand a dynamometric .device lfor 'measuring .the frictional resistance which `.tends lto oppose movement :0f said member .along with fthe vehicle, l. e., the frictional lag Aof said member with yrespect :tothe vehicle.

wheels or casters, adapted to 'cause rotation ojfza screw and a cooperating nut, respectively, through the medium of transmission gears of different ratios, movement of the Vnut along the screw being opposed lby a 'spring and v'giving a vmeasurement of `the friction coefficient of the road or Ythe like.

Preferably, the v'measurements `effected by the -device will be translated von the dashboard 'of the vehicle by putting "on or oli oneior'several signal lamps, adapted -to draw the dr'ivers attention when the road becomes dangerously slippery. v

It should however .be noted .that the ydanger involved on a :slippery road section is .greater .as the Vehicle speed increases, and the A,absolute *measurement of the friction coeilicientfs'houldfbe .integrated `with a speed measurement.

For this purpose, and according to another feature of the invention, the `.device .comprises :a speed measuring device whose .operation is associated with that of theadhesionmeasuringdevice, in order to integrate both indications and control a signal accordingly.

For example, the signal may consist of one or several special lamps, adapted'to be put on" or .off when, .at a given vehicle speed, the lroadvehicle adhesion falls below a .certain limit, or, on a road section of a given friction coeliicient,

the vehicle speed exceeds a certainilimit.

According 'tto -a `.preferred embodiment of .the

invention, vsaid lampmay befmounted in va Acircuit comprising a mercury :switch embodying :a tube, the inclination'of which maybe'altered .under the `action of a speed indicating device, and provided uwith a .number of `electrically .conducting vportions adapted to ,be energized through respective contacts, under the selective action of a movable .contact responsive .to the adhesion variations as gmeasured bythe adhesion meter.

It will be .appreciated that the dange1` involved by driving on a slippery road section increases in a descending slope and decreases in .an ascending slope. This may be very simply taken in consideration by disposing the 'longitudinal axis of `the mercury switch in parallel relation with the longitudinal .axis of the vehicle. The switch will thus operate as a level, and at the same time the mass of mercury will be responsive to the vehicle Yaccelerati'ons and .decelerations; `the imjp'ortance of this `factor on the stability of a vehicle and adhesion measuring devices are .preferably `associated with a transverse levelling .instrument fin such a manner that the latter cooperates 'in `the control of :the signal, whereby the latter will :integrate adhesion, -vehicle speed, road -convexity vand slope measurements.

.According .to a preferred Vembodiment of the invention, such a transverse level may be readily provided by devising a transversely .curved mer- .'cury switch, the electrically conducting portions 'The importance of `slowing vdown on sinuous slippry roads is well known. When the road profile is correctly inclined in a turning, the stability of the vehicle is improved and the device according to the invention gives a more optimistic information, as the mercury drop assumes a position of equilibrium under the antagonistic effects of gravity and centrifugal force.

Further features of the invention will be set forth in the following description, with reference to the accompanying drawing, given solely by example and in which:

skid. i

Fig. 2 is a diagrammatic showing of an adhesion meter embodying a pair of casters or,

friction wheels.

Fig. 3 is a section along line 3-3 of Fig. 2. Fig. 4 is an enlarged sectional view of a mercury switch controlling signal lamps mounted on the dashboard.

Fig. 5 is a transverse section of line 5 5 off' Fig. 4.

Fig. 6 is a developed plan view of the electri-v cally contacting sections of Said switch.

Fig. 7 is an enlarged detail perspective view, partly in section, of certain parts shown in Fig. 3.

Referring to Fig. 1, reference numeral I denotes an adhesion feeler, yieldingly urged by a spring 2 toward the surface or track A on which .sists of a skid pivoted to a movable carriage 6, guided in member B, spring 2 being interposed between skid I and carriage 6 and spring 3 between carriage 6 and member B.

In the embodiment of Figs. 2 and 3, the feeler consists of a pair of coaxial coasters or friction wheels 1 and 8, preferably fitted with solid tires in order that the degree of ination should not interfere with the adhesion measurements. The spindles 9 and I0 of said wheels are mounted in a casing II, extended by a tube I2, which forms one side of a deformable parallelogram, the other sides of which are constituted by two links I3 and I4 and by a rotary lever I5, adapted to pivot about a vertical spindle I6, secured to the vehicle underframe, the pivotal connections between the sides of the parallelogram being shown at I1, IB, I9 and 20. Spring 2, which is adapted to urge the wheels toward the ground A, is preferably enclosed in a telescopic tube 2|, pivoted about the axes I1 and I9.

The spindle I0 of one wheel 8 carries a bevel gear 22, meshing with a bevel gear 23, keyed to a screw 24, so mounted as to rotate about the axis of the tube I2. The spindle 9 of the other wheel 1 carries a bevel gear 25 in mesh with 'a bevel gear 26, coaxial with gear 23, and secured to one end of a rotary sleeve 21, having internal teeth 28 engaging flutes 23 cut in a nut 30, en-

vehicle to put at will the entire adhesion measuring device in operative or idling positions. Such an apparatus may be of any conventional type, and, for instance, may be adapted to raise or lower spindle I6, within the vehicle underframe, to the extent required to break or establish con tact of the wheels 'I and 8 with their track.

The operation is as follows:

As the vehicle moves, both friction wheels 1 and 8 tend to be driven in rotation at the same speed by reason of the adhesion to the ground Fig. 1 is a diagrammatic showing of an adhesion measuring device embodying a friction A. The transmission ratios between the sets of gears 22, 23 and 25, 26 being diierent, the screw and nut assume diierent angular speeds, whereby nut 30 moves along the screw against the action of spring 3. At a given instant, a balance vis'reached and the relative movement of the screw and nut is stopped, one of the friction wheels slipping on the ground. It is evident that such slipping motion, which corresponds l to the position of equilibrium of the nut, will take place for a tension of the spring which is smaller as the adhesion of the friction wheels to gagng screw 24. The dynamometric spring above indicated is interposed between nut 3U and the other end of sleeve 21.

Teeth 28 and flutes 29 are illustrated in detail in Figure 7. n

A raising and lowering apparatus, not shownw.. may be provided to allow the operator of the the ground is smaller. y Hence, the stroke of nut 30 along screw 24 will measure the degree of adhesion offered by the road, exactly as the lag of skid I in Fig. 1.

This relative movement of the nut and screw may be transmitted to the dashboard through a Bowden cable or pneumatic, hydraulic or like connection. In the example herein illustrated, it is electrically transmitted to a set of signal lamps 3I (see Fig. 4) mounted on the dashboard and adapted to be put on or off successively, according to the degree of adhesion.

For this purpose, and as illustrated in the embodiment of my invention shown in Figures 3 and 4, screw 24 may carry a series of contacts 32 and a single contact 32a; these contacts are so disposed that as nut 30 moves along the screw 24, nut 30 depresses first the single contact 32a, then successively the various contacts 32, four of these being illustrated in the drawings in Figures 3 and 4. HIhus, nut 30 closes the current between the single lead 32a and the various successive leads 32; for this purpose it may comprise, as shown in Figure 4, an inner annular "wires 35 lead to lamps 3l, while wire 35a, serving together with contact 32a and wire 33a, as return wire, connects with one terminal of a conventional current source 60, the other terminal of which is connected to lamps 3| by a wire 35h. For simplication, wires 33 and 33a are not identified separately in Figure 4, as they merely serve to connect wires 35 and 35a with contacts 32 and 32a, respectively.

Since the internal surface of nut 30 is conductive, when said nut 30 moves from the left to the leads through lamps 3|, current source .60 and the described interconnecting wires. Wires 35a and 35 may form a cable 33, as shown on fFig. v2, leading from tu-be I2 to -a connection box 49, and to lamps 3l, either directly-or through brushes and collectors associated with the Verticalspindle i6, as shown, in order to take account of the rotation of lever -l5 when the vehicle departs from the straight course.

When the adhesion is small, the stroke of nut 30 is reduced, all the contacts 32 are open and the lamps 3l are off. If the adhesion increases, the lower-most contact 32 (Fig. 4), which corresponds to left-hand contact 32 of Fig. 3, is closed, thus energizing the right-hand lamp 31, As the adhesion increases, the second, third and fourth lamps are successively on. 'When theadhesion exceeds a certain limit, the flutes 29 lescape the internal teeth 28 and the device becomes idle and is thus relieved from undue wear. This is illustrated in Fig. 7, where nut 3.0 is shown in the position which it occupies when the adhesion is suicient to cause this nut to compressiully spring 3; namely, by reference to Fig. 3, when nut 38 has moved as far as it can to the right. The device is vso designed by proper location of teeth 2,8 that at such a position oi nut 33, flutes 29 escape teeth 23, and nut 3U no longer rotates with sleeve 21; but spring 3 simultaneously pushes nut 38 back toward teeth 28 (leftward in Figs. 3 and '7). Under these conditions, nut 38, subjected to the two contrary forces of spring 3 and of teeth 28, reaches such an equilibrium vposition that the ends of flutes 29 slide over the ends of teeth 28, and nut 30 is no longer meshed to vsleeve 21.

As soon as the adhesion becomes less than that at which this disengagement of flutes 29 from teeth 28 has occurred, the `action of spring 3 prevails, flutes 29 mesh again with teeth 28 and remain geared therewith.

In the operation so far described, danger by low adhesion is called to the attention of the driver by the extinction of the lamps 3l, which are lighted when adhesion increases. If desired, the device may be so modified, by suitable and apparent rearrangement of contacts 32 and 32a, that all lamps 3l are lighted on low adhesion, and that they are turned off upon increasing adhesion; danger due to decreasing adhesion is then called to the drivers attention by the'lighting of the lamps. For this alternative, for instance, contacts 32 and 32a are opened by depression as nut 3i) `moves along its stroke (rightward in Fig. 3) and the `relative position of contacts 32 and contact 32a along the stroke of 38 is inverse from that shown in the drawings.

In order to take care of the influence of the vehicle speed upon the stability, the device `may comprise a speed indicator 31 (Fig. 4), the operation of which is associated with that of vthe adhesion feeeler 1, 8, 39, so as to control a signal integrating the adhesion and speed measurements, for example a lamp 3G which is put oif when the speed exceeds a certain limit for a given adhesion, or when the adhesion falls below a certain limit at a given speed.

In the embodiment herein represented (Figs. 2 and 4), lamp 39 is mounted in a circuit including a mercury vswitch 39, consisting of a tube of variable inclination, pivoted about an axis `All under the action of the speed indicator :31, `the latter comprising afork engaging pins 4l mounted .on thef-tube :and :actuated Eby 'the .sleeve :42 of a `centrifugal regulator 43. l'1lube539 is :provided with `lower :electricallyl .conducting esections 44, connected with contacts 32 .and `.lamps 31 by wires 45, and an :upper electrically `conducting section'46,1connectedfby a wire `41 with -flamp 3B. The-circuitof lamp l38 is completed by wiref41b, leading to that terminal of source 60 Ito which wire 35h is `valso connected.

In Fig. 2, wires 45 form-a'cable 48, connected with cable 36 by a connection box 49.

The speed indicator is so designed that oncethe vehicle is in Amotionflamp 38 is turnedon whenever speed -and adhesion a-re so correlated vthat the speed of the vehicle lis Ywithin safety limits, and that upon motion of Athe vehicle either the failure or" lamp 38-to light or, once Vlamp 38 is lighted, its subsequent extinction, indicates rthat `the' speed and adhesion are such that the stability 'of vthe vehicle is not safe. vIn Fig. 4, it "has been `assumed that the vehicle'moves -very slowly, whereby the left-hand portion of *tube39fis raised to a maximum, and thatthe'adhesion of'theroad is very low, whereby -all the contacts 32 are open, the circuits through lamp *38 lare therefore lopen, and 'lamp '38 is off, which indicates danger. As soon as ythe adherence Aof the road increases, the lowermost contact 32 (Fig. 4) closes through fthe action of the ,adhesion feeler 1,18, v.30, and the corresponding circuit through lamp 38 closes also, through the closed Contact 32 and through'the droplet 50 intubei39, which dropletmakes contact between the 'lowermost right-hand conducting section 44 and the upper conducting section-'460i tube l39 as shown in Fig. 4. Lamp l38 being on, the drivergrnay safely accelerate the yspeed ofthe vehicle.` ,Asthe speed increases, the speed-indicator 31 is rotated and tube 39pivots inthedirection of the arrow j. The mercury kdrop 50 leaves contact with the lright-hand conducting section `4l! and reaches the second ,one from the right. It the adhesion is such 'that the lowermost contact 432 is then closed, with Athe exception of the others, the circuit of lamp 38 is again open and the ,lamp is put om thus .informing the driver that the situation is again unsafe, and so on. This'is brought about vbythe fact that, as .shown ,in Fig. 4, 'the only `contact 32 through which the circuit is closed ,is the lowermost one; while the droplet 50 Vwhich would closethe circuit through lamp 38 and vlight the latter if it were at that time over the right-handconducting section 44 of tube 39, is, however, at this moment over the second section 44 from .the right which is then connected to an open contact 32; thus the circuit through lamp 38 is open under those conditions and lamp 3,8 is off. On the'other hand, if the vehicle is operating at low speed 'over a road of high adherence, then all lamps 3l are lighted, as all contacts 32 are closed through the maximum displacement ofthe adhesion feeler towards the right in Fig. 2, or towards the top in Fig. 4. The driver can then 4accelerate his speed, and this acceleration moves tube 39, through the action ofthe speed indicator 43, so ras to cause Athe droplet 50 to pass 'from right to left in tube 39 (Fig. 4)., successively closing contacts 44-46 from right to left until the left-:hand contact 44--46 is established, each time lighting lamp 38 through closed contacts 32; when the left-hand contact 44-46 is established, with a corresponding lighting oi lamp 38, the driver will know that he hasreached top speed for the high adherence then prevailing.

Safe rdriving is indicated when the speed is such that the s'lopecf -tubef39brings the'droplet Btl-over 7 that conducting plate 44 which is connected to the highest one (in Fig. 4) of such of the contacts 32 as are closed, thus showing `that speed and adherence are properly related.'

Whenever the speed is increased beyond the safe value for a given adherence, lamp 38 will go olf and will only be put on again if the speed is decreased or the adherence increased.

Tube 39, whose axis is parallel with the vehicle axis, operates as a longitudinal level, which automatically integrates the factor "road declivity in the operation.

Accelerations and decelerations of the vehicle are simultaneously taken into account, due to the inertia of the mercury drop.

In order to also take in consideration the con- `vex profile of the road in cross-section, there may be associated with the foregoing devices a transverse level, which may be advantageously consti-r tuted by tube 38 itself, which, for this purpose.'

has a curved cross-section (Fig. Moreover. the conducting sections 44 are shaped as interiitting chevrons or Vs (Fig. 6).

When the road is at, the mercury drop 50 lies in the axis of the tube at the apex of a chevron, corresponding to the lighting of lamp 38. When the road has a convex profile, the mercury drop moves laterally, thus putting off lamp 38, if the chevron wing with which it makes contact is not energized, due to an insuflicient adhesion of the road.

The same operation takes place when the vehicle is turning, under the effect of centrifugal force.

It will be seen that the device according to the invention thus integrates by relatively simple means the various factors which influence the stability of a vehicle on a slippery road, viz.:

( 1) The coemcient of adhesion of the road,

(2) The convex transverse profile of the road,

(3) The longitudinal prole of said road,

(4) The vehicle speed,

(5) The accelerations and decelerations of the vehicle,

(6) The effect of turning,

('7) The state of the tires, by a preliminary adjustment of the tension of spring 2 in proportion to the degree of wear of the tire.

Obviously, the invention is not limited to the embodiments above described, which have been given solely by way of example.

Having now described my invention, what I claim as new and desire to secure by Letters Patent is:

. 1. A device for indicating the adhesion of vehicle wheels to the surface over which said wheels travel comprising a frame rotatably mounted about a vertical axis and adapted to be drawn by a vehicle, a pair of coaxial feeling wheels carried by said frame and adapted to yieldingly engage said surface, elasticv means adapted to yieldingly urge said feeling wheels toward said surface, dynamometric means adapted to respond to the frictional drag of said feeling wheels and to indicate said frictional drag, said dynamometric means including a rotary screw and a rotary nut cooperating with said screw and adapted to selectively engage said screw in response to said fric-` tional drag, first rotation transmitting means con- 'meeting said screw and one of said feeling wheels, second rotation transmitting means connecting said nut and the other of said feeling wheels, the relation of the transmission ratios between said screw and its connected feeling wheel on the one hand and between said nut and. .itsV connected feeling wheel on the other hand being such that equal angular rotations of said feeling wheels cause unequal angular rotations of said screw and of said nut and a corresponding elastic deformation of said dynamometric means.

2. In a device as claimed in claim l, a sleeve coaxial with and surrounding said nut and interposed between said nut and its corresponding feeling wheel, said sleeve being rotatable withv said feeling wheel and slidably engaging said nut, teeth disposed on the inner surface of said sleeve, flutes disposed on the outer surface of said nut, said flutes engaging slidably between said teeth and being constructed and arranged to escape said teeth at a predetermined deformation of said dynamometric means, thereby disconnecting said nut from its said corresponding feeling wheel.

3. A device for indicating unsafe driving condition of a surface over which a vehicle travels comprising, a feeler rotatably mounted about a vertical axis and adapted to be drawn by a vehicle and to yieldingly engage said surface, dynamometric means adapted to respond to the frictional drag of said feeler, said dynamometric means including relatively movable cooperating contact members adapted to selectively engage each other in response to said frictional drag, a pivotally mounted mercury switch having spaced electrical conducting portions, speed responsive means connected to said mercury switch for adjusting same about its pivot in accordance with the speed of the vehicle to which the device may be attached, an electric circuit including a source of potential, an electrical lamp and said electrical conducting portions and controlled by said contact members whereby the lighting and extinction of said lamp is controlled by the speed, acceleration and the frictional drag of said feeler.

4. A device as claimed in claim 3 in which the longitudinal axis of said mercury switch is substantially parallel with the longitudinal axis of said vehicle.

5. A device as claimed in claim 3 in which said mercury switch is transversely curved.

6. A device as claimed in claim 3 in which said mercury switch is longitudinally curved.

'7. A device as claimed in claim 3 in which said spaced electrical conducting portions have the form of V-shaped chevrons.

8. A device for measuring the adhesion of vehicle wheels to the surface over which said wheels travel, comprising a deformable parallelogram adapted to be drawn by a vehicle and having a 1 first side rotatably mounted on said vehicle about a vertical axis, a pair of coaxial feeling wheels carried by a second side of said parallelogram opposite said first side, elastic means connecting opposite apices of said parallelogram and adapted to yieldingly engage said feeling wheels onto said surface, a casing associated with said feeling wheels and with said second side of said parallelogram, said casing enclosing dynamometric means, said dynamometric means including a rotary screw and a rotary nut cooperating with said screw and adapted to selectively engage said screw in response to said frictional drag, rst rotation transmitting means connecting said screw and one of said feeling wheels, second rotation transmitting means connecting said nut and the other of said feeling wheels, the relation of the transmission ratios between said screw and its connected feeling wheel on the one hand and between said nut and its connected feeling wheel on .75 the other hand being such that equal angular rotations of said feeling wheels cause unequal anguiar rotations of said screw and of said nut and a, corresponding elastic deformation of said dynamometric means, said dynamometric means being adapted to oppose said unequal rotations of said screw and nut.

9. A device as claimed in claim 8 further comprising a circular sleeve connected with said casing and interposed between said casing and said nut, said sleeve being positively connected with said rotation transmitting means connected with said nut; and a groove and pin locking connection between said sleeve and said nut, the length of said locking connection being less than the maximum axial stroke of said nut along said screw, said locking connection being adapted to lock said sleeve and nut in rotation and to disconnect said nut from its associated feeling wheel when said nut engages said screw beyond a predetermined length of axial stroke of said nut along said screw.

JEAN THODORE FoUFoUNIs, amas JEAN MICHEL PAILLAIS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 15 2,225,140 Walker Dec. 17, 1940 2,290,618 Bosomworth July 21. y1942 

